A doctor friend of mine told me the following interesting fact: general anaesthetic knocks out the conscious centres of your brain, but not necessarily the emotional ones. This has an effect when people are in an operating theatre. When you hear something, you see, it passes through the emotional centres before reaching the conscious ones: you feel a response a split-second before you've worked out what you actually heard. There's an evolutionary reason for this: it speeds up your reactions when you're in danger. It bypasses some unnecessary circuits, because you can start acting on pure emotion without needing to cogitate. You hear a roar and you're shinning up a tree before you consciously think 'Tiger'; you hear a shot and you're diving for cover before you consciously think 'Sniper'. Your aural wiring can save your life.

But it can also endanger it. This is the down side of the placebo effect: if you think you're not going to get well, you actually lower your chances of recovery. So, if a doctor says over an anaesthetised patient, 'I don't know why we're bothering, this guy's not going to last more than a week anyway,' the patient may, without actually knowing what he heard, lose an edge in fighting his disease and just die, where he might have recovered if he'd heard the doctor saying, 'Well, this guy's got a good chance, I reckon.' Surgeons, apparently, are briefed not to make reckless remarks over a knocked-out patient. You can kill someone with an ill-placed comment.

Now, she's a doctor and I'm not, so it's possible my brain has scrambled this information, so if any of this is garbled, blame me, not her. What's really worrying me, you see, is the idea that you can have a huge emotional fall-out from something that you didn't know had happened. Just because something isn't in your conscious mind doesn't mean it's not having an effect on you.

And given that apparent fact, what the heck are all the dreams we don't remember doing to us?